OSB archive
OSB archive

Darwin 200: virus wars

Pete Wilton

All this week we're celebrating Darwin and the advances in evolutionary theory that have built upon his work.

I asked Aris Katzourakis of Oxford's Department of Zoology about the evolutionary 'arms race' between viruses and us:

OxSciBlog: How does studying virus evolution compare to studying the evolution of larger organisms?
Aris Katzourakis: Virus evolution occurs over far shorter time frames, and can be observed on the molecular level. For example, for rapidly evolving RNA viruses like HIV or Hepatitis C, evolution can be observed during the course of an infection within a single patient, while for the Influenza virus, evolution can be observed within the human population over the years. This offers unique opportunities to study evolution in real time, while also enabling predictions about the course of viral evolution that can be applied in a public health setting.

OSB: What makes the evolution of viruses such as lentiviruses and HIV/AIDS so challenging to unravel?
AK: The lentiviruses are locked in an arms race with the immune systems of their hosts, meaning that both parties are constantly changing in order to adapt to new challenges. This effect has been called the ‘Red Queen’ effect in evolutionary biology, in reference to the statement by the character of the same new, from Lewis Carroll's book - “It takes all the running you can do, to keep in the same place”. In practical terms, this means that the genomes of lentiviruses are constantly changing, and we are still a long way from unravelling all the pressures exerted upon the virus by the immune systems of their mammalian hosts.

OSB: What does research into lentiviruses suggest about their possible future evolution and that of HIV/AIDS?
AK: Recent research from studies of endogenous lentiviruses has shown that the lentiviruses are far older and more widespread among mammals than has been previously appreciated. This implies that there may be more lentiviruses that remain undiscovered in the wild, that could potentially make the leap from infecting other mammals to infecting people. Furthermore, the realization that lentiviruses are millions of years old implies that the corresponding conflict with their hosts immune systems has been played out over this period of time. Perhaps there remain undiscovered host innate immune factors in mammalian species, resulting from this ancient conflict, that could be harnessed in the fight against HIV.

OSB: What technological advances on the horizon could transform studies of virus evolution?
AK: Ever cheaper and more rapid sequencing will undoubtedly greatly expand our knowledge of virus evolution. Coupled with this, advances in computational techniques required to make sense of this data will prove instrumental. Many exciting discoveries in virology have occurred from the most unexpected places - I suspect the most important findings of the coming years will come as a surprise to researchers in the field of virus evolution.

Dr Aris Katzourakis is based at the Department of Zoology and the Institute for Emergent Infections, James Martin 21st Century School.

Read more of our Darwin special: worms & vertebrates, humanity's roots, birds, beaks & species